1. Field of the Invention
The present invention relates to a method of manufacturing a magnetic random access memory, by using nano-imprint lithography, and also to a method of manufacturing an embedded memory.
2. Description of the Related Art
Magnetic tunnel-junction (MTJ) elements used in any magnetic random access memory (MRAM) comprise upper and lower magnetic material, and a tunnel insulating film formed between the upper and lower magnetic material. The flatness of the films greatly influences the characteristic of the MTJ element. The flatness of the MTJ element on a lower electrode must therefore be increased in order to enhance the characteristic. Further, no MTJ element can be formed immediately above a contact connected to a transistor. The alignment margin of between the MTJ element and the lower electrode can be selected. The alignment margin of between the MTJ element and the lower electrode pattern influences the memory-cell size.
A nonvolatile RAM, such as MRAM, is embedded together with logic circuits in many cases, because of its characteristic. Therefore, the memory section must be embedded between the logic-circuit layers developed. However, the wirings of the memory section and the logic section must be formed different in height, in the same plane. Consequently, the wirings of the memory section are not aligned with those of the logic section.
Jpn. Pat. Appln. KOKAI Publication No. 2007-207778 is cited herein as a prior-art document that pertains to the present invention.